ZHCSJO8 May   2019 OPA818

ADVANCE INFORMATION for pre-production products; subject to change without notice.  

  1. 1 特性
  2. 2 应用
    1.     高速光学前端
  3. 3 说明
    1.     光电二极管电容与 3dB 带宽间的关系
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics: VS = ±5 V
    6. 6.6 Typical Characteristics: VS = ±5 V
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Input and ESD Protection
      2. 7.3.2 Feedback Pin
      3. 7.3.3 Decompensated Architecture With Wide Gain-Bandwidth Product
      4. 7.3.4 Low Input Capacitance
    4. 7.4 Device Functional Modes
      1. 7.4.1 Split-Supply Operation (+4/–2 V to ±6.5 V)
      2. 7.4.2 Single-Supply Operation (6 V to 13 V)
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Wideband, Noninverting Operation
      2. 8.1.2 Wideband, Transimpedance Design Using OPA818
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Thermal Considerations
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 接收文档更新通知
    2. 11.2 社区资源
    3. 11.3 商标
    4. 11.4 静电放电警告
    5. 11.5 Glossary
  12. 12机械、封装和可订购信息
    1. 12.1 Package Option Addendum
      1. 12.1.1 Packaging Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

7.3.4 Low Input Capacitance

Often two primary considerations for TIA applications are maximizing TIA closed-loop bandwidth and minimizing the total output noise to maximize Signal-to-Noise Ratio (SNR). The total input capacitance (CTOT) of TIA circuit causes a zero in the noise gain in combination with the transimpedance gain (feedback resistor, RF) at frequency 1/(2πRFCTOT). For a fixed RF, this zero is at a lower frequency for higher CTOT thus increasing the noise gain at lower frequency resulting in lower equivalent closed-loop bandwidth and higher total output noise compared to a lower CTOT. By choosing an amplifier like OPA818 that features a low input capacitance (2.4 pF combined common-mode and differential) for TIA application, the system designer can realize high closed-loop bandwidth at low total output noise or have the flexibility to choose a photodiode with relatively higher capacitance. The CTOT includes the input capacitance of the amplifier, the photodiode capacitance, and the PCB parasitic capacitance at the inverting input.